It will be months rather than weeks before reservoirs serving Dublin are back to full capacity, officials have warned.
Officials are now faced with major headaches, with old public pipe systems leaking badly and supplies seriously depleted after householders left taps running during the big freeze.
It will be weeks before leaks can even be identified because very low pressure in the pipelines has created problems in tracing them.
With 20,000 homes in Dublin suffering water shortages, the city council confirmed it would be four months before water levels are fully restored.
Councils continue to hope for heavy rain to replenish depleted reservoirs as householders in some areas continue to experience long periods without water.
The National Emergency Response Co-ordination Committee warned that demand for water was still exceeding production capacity in Dublin and other areas.
Officials from South Dublin County Council and Fingal County Council warned that all houses would be cut off or continue to experience reduced pressure at night to help reservoirs replenish.
Dublin City Council said Walkinstown, Crumlin, Irishtown, parts of Dublin, Coolock, Artane and Finglas would have very low pressure.
Large parts of south Dublin -- including Killiney, Dalkey, Sandycove and Glasthule -- continue to suffer without a water supply.
In Limerick, Westmeath and Wexford, water shortages were causing major problems for many householders.
Sean Hogan, chairman of the National Emergency Response Co-ordination Committee said: "Demand for water is still continuing to exceed production.
"This is due to leaks in the mains. Our key concern is to preserve supply. Property owners should check and fix leaks and the public should report leaks to local authorities.
"Pressure is low and it's difficult to detect leaks. Demand has started to come down to production levels. As levels come down and pressure returns, leaks can be identified."
The Government plans to spend €508m this year on upgrading the water system, having spent €1bn in 2008 and 2009.
Labour's transport spokes-man Tommy Broughan said the crisis showed the water infrastructure in Dublin was in a "shocking state" of disrepair.
"There has been a total lack of investment in our water system," he said.
"The region needs much greater water treatment capacity and new holding reservoirs."